First evidence for a Vibrio strain pathogenic to Mytilus edulis altering hemocyte immune capacities

Type Article
Date 2016-04
Language English
Author(s) Ben Cheikh Yosra1, Travers Marie-AgnesORCID2, Morga BenjaminORCID2, Godfrin YoannORCID2, Rioult Damien3, Le Foll Franck1
Affiliation(s) 1 : Univ Le Havre, SEBIO, UMR I 02, Lab Ecotoxicol Aquat Environm, F-76063 Le Havre, France.
2 : IFREMER, LGPMM SG2M, Lab Genet & Pathol Mollusques Marins, Ave Mus de Loup, F-17390 La Tremblade, France.
3 : Univ Reims, SEBIO, UMR I 02, Lab Ecotoxicol Aquat Environm, Campus Moulin de la House, F-51100 Reims, France.
Source Developmental And Comparative Immunology (0145-305X) (Elsevier Sci Ltd), 2016-04 , Vol. 57 , P. 107-119
DOI 10.1016/j.dci.2015.12.014
WOS© Times Cited 23
Keyword(s) Innate immunity, Molluscs, Cell-mediated immune response, Bacterial infections, Green fluorescent protein
Abstract Bacterial isolates were obtained from mortality events affecting Mytilus edulis and reported by professionals in 2010-2013 or from mussel microflora. Experimental infections allowed the selection of two isolates affiliated to V. splendidus/V. hemicentroti type strains: a virulent 10/068 1T1 (76,6% and 90% mortalities in 24h and 96h) and an innocuous 12/056 M24T1 (0% and 23,3% in 24h and 96h). These two strains were GFP-tagged and validated for their growth characteristics and virulence as genuine models for exposure. Then, host cellular immune responses to the microbial invaders were assessed. In the presence of the virulent strain, hemocyte motility was instantaneously enhanced but markedly slowed down after 2h exposure. By contrast, hemocyte velocity increased in the presence of the innocuous 12/056 M24T1. At the same time interval, 10/068 1T1 invaded hemocytes and was more rapidly internalized than the innocuous strain. Extracellular products (ECPs) prepared from 10/068 1T1 cultures significantly inhibited phagocytic activity while 12/056 M24T1 ECPs had no effect. Furthermore, the pathogenic strain and its ECPs inhibited oxidative burst unlike 12/056 M24T1 strain/ECPs which enhanced ROS production. Taken together, our results suggest that the mussel pathogen 10/068 1T1 may escape immune response by altering hemocytes functions.
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